Three-phase

About: Three-phase is a research topic. Over the lifetime, 16801 publications have been published within this topic receiving 159477 citations.

Equivalence of SVM and Carrier-Based PWM in Three-Phase/Wire/Level Vienna Rectifier and Capability of Unbalanced-Load Control

Abstract: In this paper, the analysis of space vector modulation of a three-phase/wire/level Vienna rectifier is conducted, according to which the implementation of the equivalent carrier-based pulsewidth modulation is deduced theoretically within each separated sector in the diagram of vectors. The voltage balancing ability of dc-link neutral point, which depends on the uneven distribution of short vectors, is analyzed as well. An adaptive and robust controller to balance the output voltage under the unbalanced load limit for different modulation indices is proposed. The proposed controller can work at wide range of unbalanced load condition as well. Furthermore, the maximum unbalanced load is deduced versus the modulation index m when the converter works in unity power factor. An experimental prototype of 2.5 kW was built to verify the effectiveness of the theoretical analysis. Finally, the tested unbalanced limit of outputs for the experimental platform was given under different modulation indices. The output voltages for dual bus are balanced, and the theoretical analysis is verified.

Sinusoidal Three-Phase Current Reconstruction and Control Using a DC-Link Current Sensor and a Curve-Fitting Observer

Abstract: Successful operation of three-phase current controllers requires measurement of the instantaneous values of phase currents. An innovative method to estimate the three-phase currents from dc-link current is presented. A sinusoidal curve-fitting observer that does not use any of the load parameters is employed. Using the firing signals and the dc-link current for corrective action, the observer generates stable three-phase feedback signals, even during short periods when the phase current information is not present in the dc-link current.

Predictive Current Control of Three-Phase Grid-Connected Converters With Constant Switching Frequency for Wind Energy Systems

Abstract: A predictive current controller with an extended-state observer (ESO) is proposed for grid integration of wind energy systems. In each sampling period, the proposed strategy calculates the converter switching time that minimizes a cost function defined as a sum of squared current errors, leading to constant switching frequency. To achieve excellent dynamic performance, the impact of sampling delay is analyzed, and detailed compensation methods are proposed. In addition, an ESO is constructed to suppress parameter variations and modeling errors, which affect the performance of the controller. The parameter tuning and the stability of the observer are analyzed. The proposed strategy not only presents rapid dynamic response due to the use of the predictive current controller but also possesses robust control performance as a result of the observation algorithm. Simulation and experimental results are given to validate the effectiveness of the proposed solution.

Influence of phase-locked loop on input admittance of three-phase voltage-source converters

Abstract: A regulated power converter can cause instability issues at its terminals with its input filter or the source. The Generalized Nyquist stability Criterion (GNC), when applied to the product of the source impedance and load admittance in the dq frame, can be used to analyze the stability of balanced three-phase ac systems. This paper presents the influence of the Phase-Locked Loop (PLL) on the input admittance of three-phase Voltage-Source Converters (VSC) for open loop, current-feedback and voltage feedback control conditions. Analytical results show that the PLL introduces a parallel admittance to the open loop admittance of the VSC, and that the current and voltage control loop have additional effects on it. Both simulation and experimental results are presented to verify this analysis. The possible instability due to different PLL design is also shown.

A Comprehensive Study of Harmonic Cancellation Effects in Interleaved Three-Phase VSCs

Abstract: This paper presents a systematic study of the effects of interleaving on three-phase voltage-sourced converters (VSC). Analytical results are developed for the spectra of converter phase currents, common-mode voltages, and dc-link currents for the general case of interleaving N parallel modules with a common dc link. It will be shown, both analytically and numerically, that ripple cancellation effects similar to what have been widely observed in buck dc-dc converters, that is, the elimination of harmonic sidebands other than those centered at TV multiples of the carrier frequency, can also be achieved by proper interleaved operation of N three-phase VSC modules. This will be shown to be true not only for the ac phase currents, as previously known, but also for the common-mode voltage as well as the dc-link current. Analytical results are also presented for the circulating current among parallel modules. Additionally, a relationship between interleaved VSCs and capacitor-clamped multilevel converters is established and used to extend the analytical results developed for interleaved VSCs to multilevel converters.